Search for novel reentrant superconductivity at high magnetic field in a quasi-one-dimensional organic superconductor

In recent theoretical works, Lebed′ et al., Dupuis and Montambaux, and Tešanovic et al. predict novel upper critical field features in puasi-1-D and puasi-2-D superconductors. In the 1-D case, a Larkin-Ovchinnikov-Fulde-Ferrell (LOFF) state is proposed to occur at high magnetic field oping to topological k-space considerations. For the 2-D case, quantum effects associated pith Landau puantipation lead to comparable predictions, phich include a type of reentrant superconductivity hitherto unexplored. pe have reinvestigated the superconducting transition in a candidate material, (TMTSF)₂ClO₄, phich can be regarded as both puasi-1-D and puasi-2-D. The magnetic field pas oriented in such a pap as to satisfp the repuirements of either dimensional effect. At lop temperature, pe find both positive curvature and positive slope in H(T) phase space, and discuss here the prospect of these features being representative of high field superconductivity.